Semi-condyle type artificial knee joint

ABSTRACT

A semi-condylar artificial knee joint includes a femoral prosthesis and a tibial prosthesis, and the cross-section of the tibial prosthesis is of a kidney-like type. The tibial prosthesis is disposed at one side of the tibial plateau intercondylar eminence and is located below the femoral prosthesis. The artificial knee joint further includes a locating pin for fixing the tibial prosthesis. The bottom surface of the tibial prosthesis is provided with a prosthetic notch, and below the tibial prosthesis is provided with a tibial notch. The prosthetic notch corresponds to the tibial notch, and together forming a limiting hole for accommodating the locating pin. The cooperation between the locating pin and the limiting hole can ensure relative position stability and balance between the tibial prosthesis and the tibial plateau intercondylar eminence.

TECHNICAL FIELD

The invention relates to a medical artificial joint prosthesis,particularly relates to a semi-condylar artificial knee joint.

BACKGROUND ART

At present, knee replacement surgery is the world's most fundamentaltreatment for knee diseases and injuries. In replacement surgery, jointprostheses, also called artificial knee joints, are implanted into thehuman body to replace the body's natural knee joints. With the gradualadvancement of science and technology, further requirements forartificial knee joints and replacement surgery are becoming higher andhigher. People hope not only to reduce pain, but also to increase theirservice life. They also hope to achieve better postoperative recovery,and even hope to reach the level of normal healthy people. For thesereasons, various artificial knee joints have gradually come out, andvarious ideas have been proposed. However, the current mainstreamsurgical methods and artificial knee joints are far from meeting theabove requirements.

The two main leg bones of the human body are the femur and the tibia,with the femur above, the tibia below, and the position where the femurand tibia intersect and interact is the knee joint. The section of thefemur in the knee joint is called the lower end of the femur, and thesection of the tibia in the knee joint is called the upper end of thetibia; the lower end of the femur and the upper end of the tibia areenlarged, providing a support foundation for the stability of the kneejoint.

The lower end of the femur is developed into two discrete condyles, thelower surfaces of the condyles are smoothly rounded and covered inarticular cartilage. The two discrete condyles are not symmetrical, themedial condyle is larger, and the lateral condyle is smaller, so as toadapt to different stress situations of the medial and lateral sides.The upper end of the tibia comprises shallow concave lateral and medialplateau which covered with articular cartilage. The medial plateau islarger than the lateral plateau. The entire tibial plateau is separatedby an eminence or tubercle between the lateral plateau and the medialplateau.

The patella (kneecap) is embedded in the quadriceps tendon whichconnects the quadriceps musculature of the anterior upper thigh to thepatella, and the patella being connected by the patellar ligament to thetibia just beneath the knee joint. The combination of the quadricepstendon, patella, and patellar ligament acts rather like a pulley,transmitting forces generated by the quadriceps musculature to the tibiavia the flexed knee, thereby straightening the leg or decelerating therate of flexion. The patella obviously also serves the further functionof protecting the knee joint from impact damage.

The cruciate ligaments act to substantially locate the condyles on thetibia during flexion and extension. During flexion of the knee joint,tension applied by the anterior cruciate ligament restrains the condylesfrom posterior displacement. During extension of the knee joint, theposterior cruciate ligament restrains the condyles from anteriordisplacement.

The knee menisci are vital to the normal functioning of the knee joint.In addition to enhancing joint congruence, the menisci cushion anddifferentiate forces as they pass through the knee joint, reducing thefriction and impact between the femur and tibia.

However, in the current popular knee replacement surgery, the naturaltibial plateau is often directly removed, replaced with an artificialtibial plateau, and a similarly shaped femoral condyle prosthesis isinstalled on the femoral surface, so that the new femoral condyleprosthesis interact with the artificial tibial plateau, which lead tothe absence of cruciate ligaments and menisci in the knee joint aftersurgery, and some even the patella. Therefore, the current surgicalmethod and the characteristics of the corresponding artificial kneejoint make it impossible to have the desired recovery effect after suchan operation. Such surgery destroys the original physiological structureand characteristics of the knee joint, and causes permanent irreversibledamage to the knee joint. Adjustments are urgently needed and a newartificial knee joint capable of retaining the cruciate ligaments, thepatella and having a meniscus cushioning function is needed.

In addition, after years of clinical research, it is known that in kneejoint lesions, the medial condyle and lateral condyle, the medialplateau and the lateral plateau have different degrees of injury, whichare often affected by human behavior and work habits. The medial condyleor plateau is damaged first, and then the other condyle or plateau isaccelerated and the patient suffers great pain during this process. Ifsurgery is performed during this process, the side that is not damagedis often removed together because the tibial plateau and the new femoralcondyle are monolithic; moreover, most knee joint lesions are caused bymeniscus, femoral condyle or tibial plateau degeneration and wear, withminimal damage to the cruciate ligaments and the patella.

For this reason, some people have proposed to replace the existingmonolithic knee joint with a semi-condylar knee joint. Although thisidea is worth promoting, it encountered great difficulties in the actualimplementation process, which ultimately could not be achieved, or itsreal effect was lower than the original monolithic knee joint; the mainproblem is that when the semi-condylar knee joint is replaced, thereplacement part does not match the function and height of the intactpart, which cannot effectively delay the damage rate of the intact part.After the other intact part of the knee joint is also damaged, theartificial knee joint still needs to be replaced by surgery. At thistime, if the semi-condylar knee joint is also used, the twosemi-condylar knee joints are difficult to coordinate in terms ofheight, size and elasticity, and the use effect is poor. If themonolithic knee joint is used to replace, the originally replacedsemi-condylar knee joint becomes meaningless, and it also involves thesecondary damage installation of the tibia and femur.

Due to the above problems, the present inventors have made in-depthresearch on the existing artificial knee joints and devised a newsemi-condylar artificial knee joint to solve the above problems.

Contents of the Invention

In order to overcome the above problems, the present inventors haveconducted intensive research, and devised a semi-condylar artificialknee joint. The knee joint includes a femoral prosthesis and a tibialprosthesis, and said tibial prosthesis is kidney-like type in crosssection. The tibial prosthesis is disposed at one side of the tibialplateau intercondylar eminence and is located below the femoralprosthesis. The bottom surface of said tibial prosthesis is providedwith a prosthetic notch, and the tibia below said tibial prosthesis isprovided with a tibial notch. Said prosthetic notch corresponds to saidtibial notch, and forming a limiting hole together with theintercondylar eminence hole for accommodating the locating pin. Saidlimiting hole penetrates/pass through the tibial plateau intercondylareminence. The artificial knee joint further includes a locating pin thatcan be embedded in the limiting hole. Through the cooperation betweenthe locating pin and the limiting hole can ensure relative positionstability and balance between the tibial prosthesis and the tibialplateau intercondylar eminence. When two semi-condylar artificial kneejoints are installed in the medial and lateral of one knee joint at thesame time, the limiting holes in the two semi-condylar artificial kneejoints connect and share a locating pin to form a complete combined fullknee joint. Said tibial prosthesis includes an upper gasket and a lowergasket, and the lower gasket is provided with an elastic subassembly,thereby completing the present invention.

Specifically, the object of the present invention is to provide asemi-condylar artificial knee joint, characterized in that, the kneejoint includes a femoral prosthesis 1 and a tibial prosthesis 2.

Said tibial prosthesis 2 is disposed at one side of the tibial plateauintercondylar eminence 31 and is located below the femoral prosthesis 1.

Wherein, said tibial prosthesis 2 includes an upper gasket 21 and alower gasket 22.

Wherein, an elastic subassembly 6 is provided on the lower gasket 22,and through which the impact force transmitted from the femoralprosthesis 1 to the upper gasket of the tibial prosthesis 2 iscushioned, so that the upper gasket 21 has a meniscus-like function.

Wherein, said elastic subassembly 6 penetrates the lower gasket 22, andis fixed and installed on the lower gasket 22, the upper end protrudesabove the lower gasket 22 and abuts on the lower surface of the uppergasket.

Wherein, said elastic subassembly 6 includes a sleeve 61 and a spring62, the lower end of the spring 62 is buried in the sleeve 61, and theupper end of the spring is abutted on the lower surface of the uppergasket.

The sleeve 61 passes through the lower gasket 22, and the bottom end ofthe sleeve is installed in the cavity 7 of the tibia.

Wherein, a bolt 63 for adjusting the elasticity of the spring 62 isprovided at the bottom of the sleeve 61.

Wherein, said tibial prosthesis 2 is placed at the lower back of thepatella.

Wherein, the artificial knee joint further includes a locating pin 5,through which the tibial prosthesis 2 is fixed to the tibia.

Wherein, the upper portion of one end of said locating pin 5 isinstalled in the tibial prosthesis 2, and the other end thereof isinstalled in the tibial plateau intercondylar eminence 31.

Wherein, a prosthetic notch 23 is provided on the bottom of said tibialprosthesis 2.

A tibial notch 32 is provided on the top of the tibia below the tibialprosthesis 2, and

Said prosthetic notch 23 corresponds to said tibial notch 32, andtogether constitute a limiting hole 4 for accommodating the locating pin5, and the limiting hole penetrates the tibial plateau intercondylareminence 31.

The present invention provides a method for using a semi-condylarartificial knee joint described above, and the method includes thefollowing steps:

Step 1, install the femoral prosthesis 1 on the femoral condyle;

Step 2, open a space for the placement of the tibial prosthesis 2 on thetibial plateau;

Step 3, excavate a tibial notch 32 in the tibia and extend the tibialnotch 32 to the tibial plateau intercondylar eminence 31, and form anintercondylar eminence hole 33 in the tibial plateau intercondylareminence 31;

Step 4, excavate a cavity 7 in the tibia;

Step 5, insert the sleeve on the tibial prosthesis 2 into the cavity 7,and simultaneously adjust the relative positions of the prosthetic notch23, the tibial notch 32 and the intercondylar eminence hole 33, so thatthe prosthetic notch 23, the tibial notch 32 and the intercondylareminence hole 33 together constitute a limiting hole 4;

Step 6, install the locating pin 5 in the limiting hole 4, after thelocating pin 5 is fixed, the tibial prosthesis 2 is fixed by bonecement.

Wherein, preferably, before performing Step 5, adjust the elasticity ofthe spring 62 by rotating the bolt 63.

The beneficial effects of the present invention include:

(1) The artificial knee joint provided according to the presentinvention has a small tibial prosthesis and can be placed at the side ofthe tibial plateau intercondylar eminence, thereby eliminating the needto remove and destroy the tibial plateau intercondylar eminence,ensuring the cruciate ligaments on the tibial plateau intercondylareminence can be kept intact, so that greatly enhances the use effect andthe patient experience;

(2) The artificial knee joint provided according to the presentinvention has a small tibial prosthesis, and only a part of the kneejoint can be replaced according to the condition, or the prosthesis canbe transplanted in stages. The semi-condylar artificial knee jointprovided in the present application is replaced first or only one, andif necessary, another semi-condylar artificial knee joint provided inthe present application can be replaced later, and the practicalapplication is more flexible and convenient;

(3) The tibial prosthesis of the artificial knee joint providedaccording to the present invention is provided with an elasticsubassembly, which can simulate the function of the meniscus and providea cushioning effect, so that the artificial knee joint is moresubstantially similar to the natural knee joint;

(4) The elasticity/elastic force of the spring in the elasticsubassembly of the tibial prosthesis of the artificial knee jointprovided according to the present invention can be adjusted according todifferent ages and physical conditions, which can ensure that the springelasticity/elastic force is in an optimal state;

(5) The elastic subassembly of the tibial prosthesis in the artificialknee joint provided according to the present invention is arranged in adownwardly protruding tubular structure, which is embedded in the cavityon the tibia, so as to also play a role in limiting and fixing thetibial prosthesis;

(6) The tibial prosthesis of the artificial knee joint providedaccording to the present invention is provided with a prosthetic notch,and also provided with a locating pin connecting the tibial prosthesisand the tibial plateau intercondylar eminence, so that tibial prosthesisis completely fixed on the tibia, the fixing method is simple, and theeffect is good.

(7) The tibial prosthesis of the artificial knee joint providedaccording to the present invention is provided with a prosthetic notch,and a locating pin connecting the tibial prosthesis and the tibialplateau intercondylar eminence is also provided, which can allow theaddition of a semi-condylar artificial knee joint when necessary, andcan be extended and penetrated through the limiting hole, that is, theintercondylar eminence hole is changed from a blind hole to a throughhole. The two semi-condylar artificial knee joints are fixed by theoriginal locating pins, and the relative positions between the twotibial prostheses are restricted and fixed in an all-round way, so thatthe artificial knee joints have a balanced force, an overall steadystate, a long service life, and a good patient experience.

DESCRIPTION OF FIGURES

FIG. 1 shows an exploded view of a semi-condylar artificial knee jointassembly according to a preferred embodiment of the present invention;

FIG. 2 shows a schematic structural diagram of a femoral prosthesis in asemi-condylar artificial knee joint according to a preferred embodimentof the present invention;

FIG. 3 shows a schematic diagram of a sectional shape of a limitinghole/locating pin in a semi-condylar artificial knee joint according toa preferred embodiment of the present invention;

FIG. 4 shows a schematic diagram of a sectional shape of a limitinghole/locating pin in a semi-condylar artificial knee joint according toa preferred embodiment of the present invention;

FIG. 5 shows a schematic diagram of a sectional shape of a limitinghole/locating pin in a semi-condylar artificial knee joint according toa preferred embodiment of the present invention;

FIG. 6 shows a schematic structural diagram of a tibial prosthesis in asemi-condylar artificial knee joint according to a preferred embodimentof the present invention;

FIG. 7 shows a cross-sectional view of an elastic subassembly on atibial prosthesis in a semi-condylar artificial knee joint according toa preferred embodiment of the present invention;

FIG. 8 shows a schematic diagram of the tibia in a semi-condylarartificial knee joint according to a preferred embodiment of the presentinvention;

FIG. 9 shows a schematic diagram of the tibia placed with twosemi-condylar artificial knee joints in a semi-condylar artificial kneejoint according to a preferred embodiment of the present invention;

FIG. 10 shows an exploded view of the assembly of a femoral prosthesisand a femur in an artificial knee joint according to a preferredembodiment of the present invention;

FIG. 11 shows a schematic structural diagram of a femoral prosthesis anda femur assembled in an artificial knee joint according to a preferredembodiment of the present invention.

DESCRIPTION OF THE REFERENCE SIGNS

-   -   1—femoral prosthesis    -   11—anterior button cover    -   12—fixing spine    -   13—posterior button cover    -   14—fixing pin    -   2—tibial prosthesis    -   21—upper gasket    -   22—lower gasket    -   23—prosthetic notch    -   3—tibia    -   31—tibial plateau intercondylar eminence    -   32—tibial notch    -   33—intercondylar eminence hole    -   4—limiting hole    -   5—locating pin    -   6—elastic subassembly    -   61—sleeve    -   62—spring    -   63—bolt    -   7—cavity    -   8—femur

Specific Embodiments for Carrying Out the Invention

Hereinafter, the present invention will be explained in more detail withreference to figures and examples. Through these explanations, thefeatures and advantages of the present invention will become clearer.

The term “exemplary” as used herein is intended to be “serving as anexample, an embodiment, or an illustrative embodiment”. Any of theembodiments described herein as “exemplary” need not be construed aspreferred as or better than other embodiments. Although various aspectsof the embodiments are shown in the figures, it is not necessary to drawa figure in proportion unless otherwise specified.

The semi-condylar artificial knee joint provided according to thepresent invention is shown in FIG. 1. The artificial knee joint includesa femoral prosthesis 1 and a tibial prosthesis 2, wherein, the femoralprosthesis 1 is disposed at the lower end of the femur 8 and replaces apart of the bone structure at the lower end of the femur, and the tibialprosthesis 2 is disposed at the upper end of the tibia 3 and replaces apart of the bone structure on the tibial plateau at the upper end of thetibia; in this application, said tibial plateau is the surface on thetibia that contacts the lower end of the femur, and in the center of thetibial plateau is a tibial plateau intercondylar eminence 31, alsoreferred to as a eminence or tubercle, to which cruciate ligaments areattached. The tibial plateau is mainly composed of a medial plateau anda lateral plateau located at both sides of said tibial plateauintercondylar eminence.

Said tibial prosthesis 2 is used to replace the medial plateau or thelateral plateau. After said tibial prosthesis replaces the medialplateau or the lateral plateau, the height of the unreplaced part (thetibial plateau intercondylar eminence) of the tibial plateau has thesame height of the tibial prosthesis, that is, after replacing a part ofthe tibial structure through the tibial prosthesis, the tibial heightand shape have no change.

Said femoral prosthesis only has a singular-condyle, which includes ananterior button cover 11, a fixing spine 12, a posterior button cover 13and a fixing pin 14, as shown in FIG. 1 and FIG. 2.

Specifically, as shown in FIG. 10 and FIG. 11, the shape of said femoralprosthesis 1 is consistent with the shape of the replaced part of thefemur, and the outer surface is in the shape of an arc. An anteriorbutton cover 11 and a posterior button cover 13 are respectivelyprovided at two ends of the femoral prosthesis 1 to fix the femoralprosthesis 1 to the femur. Wherein, the top end of the posterior buttoncover 13 is inclined toward the anterior button cover.

When installing said femoral prosthesis, a concave prosthetic fixationarea is first excavated from the femur. After the femoral prosthesis isinstalled in the area, the area can be filled up just so that the femurcan be restored to the previous state before the prosthetic fixationarea was excavated. That is, the femoral prosthesis 1 is fixed to thefemur by being embedded in the prosthetic fixation area.

The femoral prosthesis is provided with a fixing spine 12 and a fixingpin 14 on the inner side. When the prosthetic fixation area is processedon the femur, a blind hole is also excavated in the cancellous bone atthe corresponding position. When the femoral prosthesis 1 is fastened tothe prosthetic fixation area, the fixing pin 14 is embedded in the blindhole.

At the same time, on the cancellous bone, a tapered groove/conical holeis opened near the anterior cortical bone, wherein, said anteriorcortical bone refers to the cortical bone in contact with the anteriorbutton cover 11. The specific shape and number of the taperedgroove/conical hole correspond to the shape and number of the fixingspine 12. When the femoral prosthesis is fastened to the prostheticfixation area, the fixing spine 12 is sharply inserted into the taperedgroove/conical hole.

Preferably, the pore size of the blind hole is slightly smaller than theouter diameter of the fixing pin 14 and in the process of embedding thefixing pin 14 into the blind hole, the pore size of the blind hole willbe forced to expand and compress the cancellous bone area, therebyforming a tight consolidation.

Preferably, said fixing spine 12 and fixing pin 14 may be one or more.In the present application, preferably, there are two fixing spines 12and one fixing pin 14. Accordingly, the number of the blind hole and thetapered groove/conical hole matches the number of the fixing pin 14 andthe fixing spine 12.

The area on the femur that is in contact with the anterior button cover11 and the posterior button cover 13 is the cortical bone area, whichhas high strength and toughness.

In the present invention, it is further preferred that the anteriorbutton cover 11 is adjacent to said fixing spine 12, the anterior buttoncover 11 is buckled on the outside of the cortical bone, the fixingspine 12 is inserted into the cancellous bone, and topped on thecortical bone from the inside, thereby tightening the cortical bone andforming a socket with the posterior button cover 13 and then fasten andfix on the femur. At the same time, the anterior button cover 11 andsaid fixing spine 12 together form a groove-shaped structure with aV-shaped cross section, and the cortical bone that has been ground onthe femur is pressed against the bottom of the groove-shaped structure.The fixing spine 12 and the groove-shaped structure with a V-shapedcross section jointly assist the fixation of the anterior button cover11 to the cortical bone, so that the anterior button cover 11 and theposterior button cover 13 can be buckled on the femur, which can bescientifically and reasonably make the femoral prosthesis and the femurconsolidate firmly and reliably, and can withstand a long test.

In a preferred embodiment, the surface area of the femoral prosthesis issmall, so the volume and weight are small. Specifically, the outersurface area of the femoral prosthesis 1 accounts for less than 60% ofthe outer surface area of the medial condyle of femur/lateral condyle offemur, preferably about 40% to 55%, and in this application preferablyabout 50%, which is equivalent to about a quarter of the femoralcondylar surface area.

Said femoral prosthesis is located at one side of the femoral trochlear,and the replacement of the femoral prosthesis 1 does not affect thenormal work of the femoral trochlear. Therefore, replacing the femoralprosthesis 1 has no effect on the normal work and installation positionof the patella.

In the present invention, preferably, said tibial prosthesis is locatedbelow the femoral prosthesis 1, and the tibial prosthesis replaces themedial or lateral plateau on which the lesion occurs. In order to placeand fix said tibial prostheses, it is necessary to make a certainstructural reconstruction to the tibia or the tibial plateau. When thereis only one tibial prosthesis, the reconstructed tibia or tibial plateauis shown in FIG. 8.

If the singular-condylar artificial knee joint described in thisapplication has been used, and the other semi-condylar knee joint hasalso been damaged, it needs to be replaced with another semi-condylarartificial knee joint, that is, two tibial prostheses are set on thetibial plateau. Said two tibial prostheses 2 are respectively disposedat both sides of the tibial plateau intercondylar eminence 31, replacesthe medial plateau and lateral plateau of the tibial plateau andsupports the femoral prosthesis 1. When there are two tibial prostheses,the reconstructed tibia or tibial plateau is shown in FIG. 9.

The upper surface of said tibial prosthesis 2 has inward and downwarddepressions, and similar to the medial plateau and lateral plateau on anatural tibial plateau, as shown in FIG. 1.

The cross-section of said tibial prosthesis 2 is of a kidney type or akidney-like type, and its outer contour is consistent with the excavatedpart of the tibial plateau, and the section is a horizontal section.

The cross-sectional size of said tibial prosthesis 2 is about one thirdof the cross-sectional size of the tibial plateau.

In a preferred embodiment, as shown in FIG. 1, the artificial knee jointfurther includes a locating pin 5 for fixing the tibial prosthesis 2.

Preferably, an upper portion of one end of said locating pin 5 isinstalled in the tibial prosthesis 2, and the other end is embedded inthe tibial plateau intercondylar eminence 31.

Specifically, an intercondylar eminence hole 33 is also formed in thetibial plateau intercondylar eminence. One end of the locating pin isembedded in the intercondylar eminence hole 33, the upper part of theother end is installed in the tibial prosthesis 2, and the lower part ofthe other end is installed in the tibia.

In a preferred embodiment, as shown in FIG. 6, a prosthetic notch 23 isprovided on the bottom of said tibial prosthesis 2.

A tibial notch 32 is provided below said tibial prosthesis 2; that is, atibial notch 32 is provided on the tibia/tibial plateau below saidtibial prosthesis, as shown in FIG. 8 and FIG. 9.

Said prosthetic notch 23 corresponds to said tibial notch 32, andtogether with the intercondylar eminence hole 33 constitutes a limitinghole 4 for accommodating said locating pin 5, as shown in FIG. 3, FIG.4, and FIG. 5.

When there is only one said tibial prosthesis 2, that is, asingular-condylar artificial knee joint, said limiting hole extends intothe tibial plateau intercondylar eminence 31, and does not penetratesaid tibial plateau intercondylar eminence 31, that is, theintercondylar eminence hole 33 is a blind hole.

In a preferred embodiment, the length value of the locating pin isgreater than the length value of one prosthetic notch 23 on the tibialprosthesis 2, and the length value of the locating pin is less than thesum of the length value of one prosthetic notch 23 and the width valueof the tibial plateau intercondylar eminence 31. Therefore, when thereis only one tibial prosthesis, the locating pin can satisfy thepositioning and fixing effect. When a second semi-condylar artificialknee joint is installed on the same joint, that is, when another tibialprosthesis is added, the length of said limiting hole 4 is naturallyextended, that is, when installing the second tibial prosthesis, extendthe original limiting hole, change the intercondylar eminence hole froma blind hole to a through hole. Wherein, in a preferred embodiment, thelocating pin can be further moved into the extended limiting hole, andcompletely penetrates the tibial plateau intercondylar eminence 31ultimately. Both ends of the locating pin are embedded in the prostheticnotch 23 and play a role in limiting and fixing the tibial prosthesis 2.In another preferred embodiment, the original locating pin is taken out,a longer locating pin is replaced, and it is also inserted into thelimiting hole; preferably, the original locating pin is not replaced inthe present invention, and push the original locating pin inward tocomplete the limit fixing.

Preferably, the width value of the tibial plateau intercondylar eminence31 is less than or equal to the length value of the prosthetic notch 23.

When installing a second singular-condylar artificial knee joint, saidlimiting hole penetrates the tibial plateau intercondylar eminence 31,and the two limiting holes corresponding to the two tibial prostheses 2connect with each other to form a longer limiting hole. Preferably, saidlimiting hole 4 and locating pin 5 penetrate the tibial plateauintercondylar eminence 31 and connect the two tibial prostheses 2; thatis, in the axial direction of said limiting hole 4, the limiting hole ismade up of three parts, wherein, the two parts at the two ends areenclosed by the prosthetic notch 23 above and the tibial notch 32 below;and the third part in the middle is completely an intercondylar eminencehole 33 opened on the tibial plateau intercondylar eminence 31.

It is worth noting that due to the presence of the locating pin, it canfix the horizontal height of the two tibial prostheses 2 at both sidesof the tibial plateau intercondylar eminence, and can also make a tibialprosthesis at one side of the tibial plateau intercondylar eminence andthe tibial plateau intercondylar eminence is maintained within a desiredhorizontal height range, so that the physiological height of the kneejoint femur after replacement is basically consistent with thephysiological height of the knee joint femur before replacement. Thefixation of the tibial prosthesis 2 is performed on this basis, so thatthe tibial prosthesis is in a reasonable position to ensure that thepostoperative patient experience is good.

In a preferred embodiment, as shown in FIG. 3, FIG. 4 and FIG. 5, thecross-sectional shape of said limiting hole 4 is consistent with thecross-sectional shape of the locating pin 5; the cross-sectional shapemay be various shapes such as oval, square, trapezoid, rhombus,triangle, pentagon, pentagram, hexagon, octagon, etc. Among the variouscross-sectional shapes of the locating pin, the use effect of triangle,square, trapezoid, and polygons is better. In the present invention, atrapezoid is preferable, the trapezoidal upper bottom is located in theprosthetic notch 23, the lower bottom is located in the tibial notch 32,and the length of the upper bottom is greater than the length of thelower bottom.

In a preferred embodiment, the cross-sectional size of said locating pincorresponds to the cross-sectional size of the limiting hole, andbetween the two is a close fit, preferably an interference fit; therebymaking it difficult to continue to extend and got stuck after thelocating pin is embedded to a certain depth. At this time, the locatingpin just stays at the desired position, preferably, the position is thecenter position and will not deviate to both sides.

In a preferred embodiment, the cross-sectional size of said locating pincorresponds to the cross-sectional size of the limiting hole, and thelocating pin can be embedded in a corresponding depth position of thelimiting hole. Said locating pin may be provided with an expansion bolton an end surface, and when the locating pin is located in desiredposition, preferably the center position, the expansion bolt is screwedso that the locating pin is locked and fixed in the limiting hole,thereby making sure that the locating pin is securely positioned andwill not deviate to both sides.

In a preferred embodiment, the cross-sectional size of said locating pinis uniform, but the cross-sectional size of the limiting hole ischanged. The locating pin is provided with an expansion bolt on an endsurface and insert into the limit hole from the larger-sized side, afterthe locating pin is embedded to a certain depth and difficult tocontinue to extend, the locating pin can stay at the desired position,and at this time, the expansion bolt is screwed, so that the locatingpin is stuck and fixed in the limiting hole making the locating pinfixed more stable.

In the present invention, said locating pin is one or more, and eachlocating pin is matched with a limiting hole. When there are multiplelocating pins, there are also multiple limiting holes; the number oflocating pins is consistent with the number of limiting holes.

Said tibial prosthesis 2 is placed at the position of the anterior upperend face of the tibia and the lower back of the patella. Preferably, thesetting position of the tibial prosthesis 2 is maintained at apredetermined distance from the lower edge of the patella, and thedistance value between the natural tibia plateau and the patella isequal to the predetermined distance value. Replacing the natural tibialplateau with the tibial prosthesis 2 has no substantial impact on thepatella itself and does not affect the patella's sliding. The naturaltibial plateau referred to in the present application refers to a tibialplateau that grows naturally in a human body, where natural meansnaturally existence.

In a preferred embodiment, as shown in FIG. 6 and FIG. 7, said tibialprosthesis 2 includes an upper gasket 21 and a lower gasket 22, and theupper gasket 21 and the lower gasket 22 are fixed by means of bolts, pinrolls and so on, thus making the upper gasket 21 and the lower gasket 22have a certain relative displacement between the two in the verticaldirection and cannot be relatively moved in other directions.

An elastic subassembly 6 is provided on the lower gasket 22. The elasticsubassembly 6 buffers the impact force transmitted from the femoralprosthesis 1 to the upper gasket 21 of the tibial prosthesis 2 so thatthe upper gasket 21 has a meniscus-like function. Said meniscus iscartilage tissue in a human knee joint that plays a role in bufferingand shock absorption. Specifically, when the femoral prosthesis 1transmits an impact force to the tibial prosthesis 2, the upper gasket21 receives the impact force first, and cause the upper gasket 21 tomove downward, thereby compressing the elastic subassembly 6, and as thereaction force of the elastic subassembly 6 gradually increases, thespeed of the upper gasket 21 moves downward becomes smaller and smaller,and the impact force thereon also gets smaller and smaller, eventuallythe upper gasket presses against the lower gasket, and togethertransmits the force to the tibia. Due to the cushioning of the elasticsubassembly 6, the force corresponding to the loss of the tibia can beignored, thereby achieving a meniscus-like buffer effect, which iscalled to have a meniscus-like function.

In the present application, said elastic subassembly 6 may include aspring, and may also include a subassembly such as an airbag and acushion gasket and so on that have certain elasticity and can play arole in cushioning and absorbing shock. The elastic subassembly 6 isdisposed below the upper gasket 21 and can buffer the impact forcetransmitted from the upper gasket 21, and can select an appropriatespecific placement position according to specific structuralcharacteristics.

The following description uses an elastic subassembly including a springas an example;

Said elastic subassembly 6 penetrates and is fixed on the lower gasket22, a part of the elastic member 6 located above the lower gasket 22 isabutted on the lower surface of the upper gasket 21, and a part of theelastic subassembly 6 located below the lower gasket 22 is columnar.

Preferably, specifically, as shown in FIG. 7, said elastic subassembly 6includes a sleeve 61 and a spring 62,

wherein, the lower end of the spring 62 is buried in the sleeve 61, andthe upper end of the spring is abutted on the lower surface of the uppergasket, thus making the force transmitted from the femoral condyleprosthesis to the upper gasket 21 buffered by the spring 62 beforeacting on the lower gasket 22;

In the present invention, said prosthetic notch 23 is opened on thelower gasket 22.

In a preferred embodiment, said sleeve 61 is embedded in a cavity 7opened on the tibia 3. Preferably, the cross-sectional shape of thecavity is consistent with the cross-sectional shape of the sleeve 61,and the cross-sectional size is also the same. The two can be closelyfitted, so that the relative position between the tibia and the tibialplateau prosthesis is stable without relative displacement. Thecross-sectional shapes of the sleeve 61 and the shape of the cavity 7may be polygon, quadrangle, triangle, oval, circular, and so on. In thepresent invention, the cross-sectional shape is preferably circular.

Said sleeve can not only play a role in protecting the placement of thespring, but also can play a role in limiting and fixing the tibialprosthesis 2, thereby making the overall structure of the tibialprosthesis 2 simple and simplifying the process of placing and fixingthe tibial prosthesis.

In the present invention, preferably, said spring 62 is always in anon-stretched state.

In a preferred embodiment, as shown in FIG. 7, a bolt 63 is provided atthe bottom of said sleeve 61, and the bolt 63 can move in the verticaldirection as it rotates. Inside the sleeve 61, the top of said bolt isagainst the bottom of the spring 62, so that the elasticity of thespring 62 can be adjusted by controlling the position of the bolt 63 inthe vertical direction. The bolt 63 moves upward in the verticaldirection, the spring 62 is compressed, the elasticity of the spring 62increases; the bolt 63 moves downward in the vertical direction, thedegree of compression of the spring 62 decreases, and the elasticity ofthe spring 62 decreases, so that the appropriate spring elasticity orcalled spring tension can be adjusted according to the patient age andphysical condition, the elasticity between the upper gasket 21 and thelower gasket 22 is consistent with the elasticity of the meniscus, thetotal height/thickness of the upper gasket 21 and the lower gasket 22 isconsistent with the height of the side the artificial knee joint has notbeen replaced, and also the total height/thickness of the upper gasket21 and the lower gasket 22 of the second installing semi-condylarartificial knee joint is consistent with the height of the tibialprosthesis 2 of the semi-condylar artificial knee joint replacedpreviously, thereby solving the problem of inconsistency in height andelasticity between the medial tibial plateau prosthesis 201 and thelateral tibial plateau prosthesis 202 that are replaced in two times,and making good effect after batch operation.

In a preferred embodiment, a scale line is engraved on the bottom of thesleeve 61 and/or near the bolt 63, so that the screwing degree of thebolt 63 can be read directly through the scale line, therebyfacilitating the adjustment of the spring tension when placing theelastic subassembly 6.

Preferably, said spring 62 includes a top block provided on the top tocontact the upper gasket 21.

In the present invention, said spring 62 may be made of materials suchas metals and various high molecular polymers.

The present invention provides a method for using a semi-condylarartificial knee joint.

The artificial knee joint is the semi-condylar artificial knee jointdescribed above, and the method includes the following steps:

Step 1, open a space for the placement of the tibial prosthesis 2 on thetibial plateau. Preferably, the space is located at one side of thetibial plateau intercondylar eminence 31, and in the process of openingthe space, there is no damage to the tibial plateau intercondylareminence 31 and the cruciate ligaments thereon, and further preferably,it will not cause damage to the patella and the quadriceps tendon whereit is located.

Step 2, excavate a tibial notch 32 in the tibia and extend the tibialnotch 32 to the tibial plateau intercondylar eminence 31; form anintercondylar eminence hole 33 on the tibial plateau intercondylareminence 31; excavate a cavity 7 in the tibia. The number of the tibialnotch 32 and the cavity 7 is not fixed, and may be one, two or more, andpreferably, both select one.

Step 3, insert the sleeve on the tibial prosthesis 2 into the cavity 7,and simultaneously adjust the relative positions of the prosthetic notch23, the tibial notch 32 and the intercondylar eminence hole 33 so thatthe prosthetic notch 23, the tibial notch 32 and the intercondylareminence hole 33 together constitute a limiting hole 4.

Step 4, install the locating pin 5 into the limiting hole 4.

Step 5, fix the height position of the tibial prosthesis 2 by thelocating pin 5, and further fix the height of the tibial prosthesis 2 byadjusting the injection amount of bone cement.

Preferably, before performing Step 3, adjust the elasticity of thespring 62 by rotating the bolt 63, wherein, the elasticity/strength ofthe spring is also detected by using an elasticity detection device toensure that the elasticity/strength of the springs in the plurality ofthe elastic subassemblies 6 are consistent.

Preferably, it further includes the following optional steps:

Step a, assemble the upper gasket 21, the lower gasket 22, and theelastic subassembly 6 into a complete tibial prosthesis 2,

Step b, install the femoral prosthesis 1, wherein, the femoralprosthesis is fixed on the femur, located above the tibial prosthesisand in contact with the tibial prosthesis; preferably, excavate theprosthetic fixation area in said femur first, and then embed the femoralprosthesis into this area. Because the femoral prosthesis has a specialcurvature, an anterior button cover 11 and a posterior button cover 13,the femoral prosthesis can be fastened to the femur, and at the sametime, the fixing spine 12 on the femoral prosthesis is inserted into thefemur cancellous bone, the fixing pin 14 on the femoral prosthesis isembedded in the blind hole excavated from the femur, so as to achievethe fixation between the femoral prosthesis and the femur.

Optionally, after the installation of the semi-condylar artificial kneejoint is completed, if necessary, another artificial knee joint may befurther installed on the knee joint.

If the previous knee joint replaces the medial plateau of the tibialplateau, the posterior knee joint replaces the lateral plateau of thetibial plateau. If the previous knee joint replaces the lateral plateauof the tibial plateau, and the posterior knee joint replaces the medialplateau of the tibial plateau.

When installing another new semi-condylar artificial knee joint, theabove steps are repeated, wherein the limiting hole 4 in step 3coincides with the previous limiting hole, and the intercondylareminence hole 33 is changed from a blind hole to a through hole.

The locating pin 5 in Step 4 is the locating pin in the originalsemi-condylar artificial knee joint, continues to push the positioningpin so that it passes through the tibial plateau intercondylar eminenceand located at the center of the knee joint, and the two ends of thelocating pin are respectively embedded in two tibia prostheses.

The present invention has been described above by combing the preferredembodiments; however, these embodiments are exemplary and only serve asillustrative. On the basis of the present invention, variousreplacements and improvements are permitted, and will be seen in thescope of the present invention.

What is claimed is:
 1. A semi-condylar artificial knee joint,characterized in that, the knee joint includes a femoral prosthesis (1),and a tibial prosthesis (2), wherein said tibial prosthesis (2) isconfigured to be disposed at one side of a tibial plateau intercondylareminence and is located below the femoral prosthesis (1); said tibialprosthesis (2) includes an upper gasket (21) and a lower gasket (22),wherein, an elastic subassembly (6) is provided on the lower gasket(22), and through which the impact force transmitted from the femoralprosthesis (1) to the upper gasket of the tibial prosthesis (2) iscushioned, so that the upper gasket (21) has a meniscus-like function;said elastic subassembly (6) penetrates the lower gasket (22), and isfixed and installed on the lower gasket (22), upper end of elasticsubassembly (6) protrudes above the lower gasket (22) and abuts on lowersurface of the upper gasket; said elastic subassembly (6) includes asleeve (61) and a spring (62), lower end of the spring (62) is buried inthe sleeve (61), and upper end of the spring is abutted on the lowersurface of the upper gasket, the sleeve (61) passes through the lowergasket (22), and bottom end of the sleeve is configured to be installedin a cavity (7) of tibia.
 2. The semi-condylar artificial knee jointaccording to claim 1, characterized in that, a bolt (63) for adjustingthe elasticity of the spring (62) is provided at the bottom of thesleeve (61).
 3. The semi-condylar artificial knee joint according toclaim 1, characterized in that, said tibial prosthesis (2) is placed atthe lower back of the patella.
 4. The semi-condylar artificial kneejoint according to claim 1, characterized in that, the artificial kneejoint further includes a locating pin (5), through which the tibialprosthesis (2) is configured to be fixed to the tibia.
 5. Thesemi-condylar artificial knee joint according to claim 4, characterizedin that, upper portion of one end of said locating pin (5) is installedin the tibial prosthesis (2), and other end thereof is configured to beinstalled in the tibial plateau intercondylar eminence.
 6. Thesemi-condylar artificial knee joint according to claim 1, characterizedin that, a prosthetic notch (23) is provided on bottom of said tibialprosthesis (2), the tibial prosthesis (2) is configured to be providedon the top of a tibial notch of the tibia, and said prosthetic notch(23) corresponds to a subject being configured to be the tibial notch,and together constitute a limiting hole (4) for accommodating thelocating pin (5), and the limiting hole penetrates a subject beingconfigured to be the tibial plateau intercondylar eminence.
 7. A methodof using the semi-condylar artificial knee joint according to claim 1,characterized in that, the method includes the following steps: installthe femoral prosthesis (1) on the femoral condyle; open a space for theplacement of the tibial prosthesis (2) on the tibial plateau; excavate afirst subject being configured to be tibial notch in the tibia andextend the first subject being configured to be the tibial notch to thetibial plateau intercondylar eminence (31), and form an intercondylareminence hole (33) in the tibial plateau intercondylar eminence (31);excavate a second subject being configured to be the cavity in thetibia; optionally, but preferred, adjust elasticity of a spring (62) byrotating the bolt (63); insert the sleeve on the tibial prosthesis (2)into the second subject being configured to be the cavity, andsimultaneously adjust relative positions of a prosthetic notch (23), thefirst subject being configured to be the tibial notch and theintercondylar eminence hole (33), so that the prosthetic notch (23), thefirst subject being configured to be the tibial notch and theintercondylar eminence hole (33) together constitute a limiting hole(4); install the locating pin (5) in the limiting hole (4), after thelocating pin (5) is fixed, the tibial prosthesis (2) is fixed by bonecement.